GOES-16 water vapor imagery over far northern Canada

August 1st, 2018 |

GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images [click to play animation | MP4]

GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images [click to play animation | MP4]

Animations of GOES-16 (GOES-East) Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (above) showed features moving eastward across Nunavut in northern Canada on 01 August 2018. These images covered the far northern portion of the GOES-16 Full Disk view in AWIPS, and depicted frontal wave disturbances within the polar jet stream over that region.

Due to the large satellite viewing angle or “zenith angle”, the 2 km water vapor image pixel dimension (at satellite sub-point) increased to around 6.4 km or 4 miles (below).

Magnified view of GOES-16 Mid-level (6.9 µm) Water Vapor image, showing the pixel dimension over Nunavut, Canada [click to enlarge]

Magnified view of a GOES-16 Mid-level (6.9 µm) Water Vapor image, showing the pixel dimension over Nunavut, Canada [click to enlarge]

Another effect of the large satellite view angle was a shift of the Water Vapor weighting functions to higher altitudes — plots of the 7.3 µm, 6.9 µm and 6.2 µm weighting functions calculated using 12 UTC rawinsonde data from Baker Lake, Nunavut are shown below. These plots depict the layers of the atmosphere from which emitted radiation was detected by each of the 3 Water Vapor spectral bands on the ABI instrument.

GOES-16 Water Vapor weighting function plots calculated using 12 UTC rawinsonde data from Baker Lake, Nunavut [click to enlarge]

GOES-16 Water Vapor weighting function plots calculated using 12 UTC rawinsonde data from Baker Lake, Nunavut [click to enlarge]

Iceberg near Innaarsuit, Greenland

July 20th, 2018 |

Landsat-8 False Color RGB image swaths, zoomed in to show the iceberg near Innaarsuit, Greenland [click to enlarge]

Landsat-8 False Color RGB image swaths, zoomed in to show the iceberg near Innaarsuit, Greenland [click to enlarge]

Landsat-8 False Color Red-Green-Blue (RGB) images viewed using RealEarth (above) is zoomed in (final image) to show a large iceberg (snow and ice appear as cyan) near the island community of Innaarsuit, Greenland (shades of light green) on 20 July 2018. Media stories about this iceberg can be found here and here.

Cape Newenham, Alaska bow shock waves

June 10th, 2018 |

GOES-15 Visible (0.63 µm) images, with hourly plots of wind barbs [click to play animation]

GOES-15 Visible (0.63 µm) images, with hourly plots of wind barbs [click to play animation]

GOES-15 (GOES-West) Visible (0.63 µm) images (above) showed patches of fog and low stratus moving southwestward off Southwest Alaska and across the adjacent offshore waters of the Bering Sea on 10 June 2018.

A closer look using 250-meter resolution Terra/Aqua MODIS and 375-meter resolution Suomi NPP VIIRS true-color Red-Green-Blue (RGB) images from RealEarth (below) revealed a packet of “bow shock waves” created as the shallow fog/stratus interacted with the relatively rugged terrain of the narrow Cape Newenham land feature (Google Maps). Other examples of similar bow shock wave cloud features have been documented here, here and here.

Terra MODIS, Aqua MODIS and Suomi NPP VIIRS true-color RGB images [click to enlarge]

Terra MODIS, Aqua MODIS and Suomi NPP VIIRS true-color RGB images [click to enlarge]

A 30-meter resolution Landsat-8 false-color RGB image (below) provided a more detailed view of the bow shock wave structure. Snow cover (cyan) could be seen on some of the higher-elevation land features.

Landsat-8 false-color RGB image [click to enlarge]

Landsat-8 false-color RGB image [click to enlarge]

A time series plot of Cape Newenham surface observations (below) showed the fluctuations in visibility as northerly winds brought patches of fog over the site.

Time series plot of Cape Newenham surface observations [click to enlarge]

Time series plot of Cape Newenham surface observations [click to enlarge]

Strong storm in the Bering Sea

November 26th, 2017 |

Himawari-8 Lower-level (7.3 µm, left), Mid-level (6.9 µm, center) and Upper-level (6.2 µm, right) Water Vapor images, with hourly surface wind gusts (knots) plotted in red [click to play MP4 animation]

Himawari-8 Lower-level (7.3 µm, left), Mid-level (6.9 µm, center) and Upper-level (6.2 µm, right) Water Vapor images, with hourly surface wind gusts (knots) plotted in red [click to play MP4 animation]

Himawari-8 Lower-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (above) showed a strong storm as it was rapidly intensifying south of the Aleutian Islands and moving into the Bering Sea during the 25-26 November 2017 period (surface analyses), producing hurricane force winds. Hourly surface wind gusts (knots) are plotted in red on the images.

GOES-15 (GOES-West) Visible (0.63 µm) images during the daylight hours of 25 and 26 November (below) offered a more detailed view of the storm. As with the water vapor images above, hourly surface wind gusts (knots) are plotted in red on the images.

GOES-15 Visible (0.63 µm) images, with hourly surface wind gusts (knots) plotted in red [click to play animation]

GOES-15 Visible (0.63 µm) images, with hourly surface wind gusts (knots) plotted in red [click to play animation]

A plot of hourly surface observations from Adak Island in the Aleutians is shown below. Peak wind gusts of 91 mph were reported on Adak Island and at Unalaska.

Time series of surface observations for Adak, Alaska [click to enlarge]

Time series of surface observations for Adak, Alaska [click to enlarge]

Also of note: the surface pressure at St. Paul Island dropped to unusually low levels as the storm moved into the Bering Sea.

Time series of surface observations from St. Paul Island [click to enlarge]

Time series of surface observations from St. Paul Island [click to enlarge]